Hitherto, there have been known many techniques for amplifying DNA and RNA and for synthesizing protein. The techniques, for example, include a technique for amplifying DNA fragments of a total volume of 5 to 100 .mu.L in a plastic reactor, using DNA polymerase as an enzymatic catalyst, or one for synthesizing protein in the. similar volume without an organism.
In the present specification, the amplifying technique performed in a volume of lower than several microliters (e.g. about 5 .mu.L) is referred to as "reaction in microspace". The amplifying technique called as "reaction in microspace" can complete the reaction in a very small volume and increase its reactivity.
Recently, there has been intensely studied a method for amplifying DNA fragments using enzyme in an artificially created microspace, because it is more effective than the methods conducted through chemical reaction or using organisms The method conducted through chemical reaction has a limit in reactivity and is very difficult to synthesize long DNA fragments. In the case of the amplification using organisms, it is very difficult to synthesize long DNA fragments containing nucleotide analogues because of employing merely nucleic acids naturally oriented. The amplification using organisms also has some problems, for example, the difficulty in screening from the organism to find useful substance. If a conventional small test tube is used as a reactor, it takes a long time to dispense the starting materials into each test tube. In view of the size of the amplifying and screening facilities, the amplification in the test tube needs a large space for reacting and screening.
The method using the artificially created microspace, however, is simple and useful and does not have the above-mentioned problems, in comparison with the methods conducted through chemical reaction or using organisms.
One example of the artificially created microspace is a microcapsule formed from polypyrrole. The polypyrrole capsule is used in the amplification of DNA fragments by encapsulating DNA fragment amplifying components with polypyrrole film using interfacial polymerization. However, the polypyrrole belongs to synthetic polymer and therefore does not have sufficient biocompatibility.
Another method is proposed in which liposome is employed as encapsulating film instead of polypyrrole. Liposome is a bilayer lipid membrane which can be artificially obtained and has similar composition to the cell membrane. It is therefore believed to have high biocompatibility. However, in encapsulating with the liposome, it is difficult to control a size of the capsules. In addition, since the liposome capsules are very soft and fragile, the capsules are easily broken by physical impact given during working, e.g. pinching with a tweezers, and the like.